Means for regulating water-pressures in long underground tail-races.



R. D. JOHNSON. MEANS r011 nmuu'rmu WATER ranssunns IN LONG unnsaoaounn TAIL mass.

APPLXOATIOI TILED IA]. 0, 1913.

Patented Feb. 1 7, 1 9 14.

INVENTOR WITNESSE 6? /6% D. JOHNSON, OF NIAGARA FALLS, NEW YORK.

iu ANs iron g nqULArrno wA'rnnrrnnssunns IN Lone UunEnsRoUnn TAIL-RACES.

Specification of Letters Patent.

Patented Feb. 1 7, 19 14.

Application filed January 6, 1313. Serial No, 740,568.

T0 at! whom it may concern Be it known that LRAYMoN-n D. JOHNSON, a citizen of the United States, residing at Niagara Falls, in the county of Nia ara and State of New York, have invente certain new and useful Im rovemeuts in Means .for

Regulating Water-- ressu rcs in Long Undergroun" Tail-Races, of whic'h the following is a s )ecification.

*his invention relates to apparatus for assisting the speed-regulation of turbines in tail-race, when the wheel-gates are suddenly opened or closed. v.

\Vhen the water escaping from a turbine is carried away by a long underground tailrace', running full with air excluded, and with the water therein under pressure, difiiculty arises when the turbine-gates are shifted to compensate for changes of load. The.

sudden requisition made uponthe tail-race to deliver more or less water, which can only be satisfied by a rapid acceleration or retardation of the velocity of the long column of water therein, causes an abrupt and severe change of water-pressure, which not only renders wheclspecd regulation or lremely difiicult or impossible, but may result in damage to the plant. For example, it the gates are suddenly closed, the inertia of the column of effluent water may momclr tarily draw a vacuum underneath the turbine, after which the column of w'ater will surge backward to fill the vacuum, producing a dangerous watcr-lmmmcr in the draftchamber of the turbine. Conversely, when 'the gates are suddenly opened, the effort to impossible for most commercial purposes,

This retardation of wheel-speed will be quickly followed by a rapid and dangerous rise of speed, due to the subsequent reduction of pressure caused by the outward pendulum-hke swing of the long water-column 'Qn account of 'thesediliicultics in operatihg a' p'lmit having-a long underground tail race when the race is run full, it is the usual practice to make the race or tunnel of a cross-section much eater than that necessary for-the economical discharge of the water, and to carry its mouth into the river above the high-\vater-inark, thereby allowing air to enter the mouth and causing a space filled with air to exist above the stream of Water at all points in the tamnel, back to the turbine draft-tube. While satisfactory Wheel-regulation is thus obtained, it is at a great sacrifice of water-head and with a large initial expense for excavation.

The present invention is a hydraulic regulator connected. to the turbine draft-tube,or to the tail-race in proximity to the turbine, which mitigates the abrupt changes of wator-pressure in the race due to the sudden shifting of the wheel-gates, thereby enabling a race of minimum radlent and crosssection tobe run full 0 water at high velocities.

The preferred apparatus is shown in the accompanying drawing, in which the figure 7S atransver'sc vertical section of a waterpower plant, the plane of section passin through the wheel-pit, regulator-pit, tai race and regulator supply-passage, the turhim being shown in elevation and the regu lator in axial section.

This installation comprises a vertical wheel-shaft 1, on-the base of which is seated a turbine 2, fed by a penstock 3. The water from the turbine escapes through a vertical draft-tube 4, shown as a passage through the concrete base, into a tailrace 5. The mouth 6 of this race opens into the riverbed'7 at the low-wuter-level. At one side of and opening into the wheel-shaft is the regulator-pit 8.

The hydraulic regulator comprises a vertical tank 9, preterably a cylindrical tank loo the river "by an amount corresponding to the head required toovercome the Waterlosses'due to friction arndimpact, the dotted linen joiningthe two-levels 12:12 banana.

45 opening 10.

hydraulic gradient. If now a sudden change of load is demanded, the immediate water requirement of the race, either plus or minus, will be furnished by the tank, acting as a 3 storage reservoir, and the necessary accel oration. or retardation of the long column of water in the race will be gently effected the gradual increase or decrease of pressure within the tank, as the level rises or falls in therein. Otherwise stated, the excess or deiiciency of water temporarily not cared for by the tail-race will be stored in or supplied by the tank. While such a. sirnple'storagetank is operative as a regulator, it is subject to the disadvantage that the long column of water in the race acts as a pendulum, in which, when once set into -vibration by a change of load, thevelocity changes tend to oscillate back and forth, even if there is no further change in the position of the wheelgates And if the gates are shifted by their speed-regulator in synchronism with this endulum-iike swing, the amplitude of oscil ation is thereby greatly increased and undue pressure-changes will result. To overcome this oscillation of the column of water in the race, it is preferred to interpose between the regulator-tank and the tail-race a. resistance or restricted passage for the water.- And in so order to mitigate the sudden changes of pressure which would otherwise be caused by this restriction, a stand-pipe is provided, which itself has some water-capacity and in which the water changes its level somewhat as gradually, rising or falling therein to a point where the pressure due to the difference in the levels in the tank and the stand-pipe is suiiicient to force through the restricted opening the excess or deficiency of water to an be temporarily cared for. In the apparatus tion of the pressure-level therein and the level of water outside in the storage-tank, acts like a dash-pot, to damp the oscillation of the water through the passage 11, between the tail-race and regulator, greatly reducing as the amplitude of the vibration; in fact, with proper design, its action may be dead-beat, entirely doing away with the pendulum-like swing of the column of water in the race, a load chcnge producing but one swing or so change of level in the tank, corresponding simply to the unavoidable change in by draulic gradient following the load ehange. The mathematical theory of the diiierential action of this stand-pipe has been fully at described by me in an article, No. P2045, en-

titled The surge tank in water power plants, published by the American Society of Mechanical Engineers. The principle is similar to that utilized in my apparatus for cushioning hydraulic pressures in turbine penstocks, covered by my U. S. Letters Patent No. 962,355, granted June 21, 1910.

While the staud-pipe 15 preferably extends above the tank 9, to permita very considerable rise of the pressure-level therein, the use of a ingle imperforate pipe is disadvantageous, on account of the large vol umes of water which might be projected from the top of such pipe when the demand for power is suddenly increased, falling back into the tank from a considerable height with a heavy hammering action. It is therefore preferred to provide outlet passages between the lower and upper ends of this pipe, and not far above the normal level of water in the tank. While a single pipe having openings through its wall may be employed, it is preferred to use a double stand-pipe, the upper section 15 hi which is of smaller diameter than the lower section, the lower end of the upper section being fixed concentrically in the 11 per end of the main pipe to leave an annu ar passage 18, through which the bulk of the water rising in the pipe 15 may escape into the tank. It will be noted that the annular passages 17, 18 are in line with the normal flow of water, and set up no eddy-currents to interfere with the normal damping action.

I claim:

1. In combination with a water-power plant comprising a water-wheel and a long closed tail-race, a regulator consisting of a storage-tank connected to the tail-race in proximity to the Water-wheel.

2. In combination with a water-power plant comprising a water-wheel and a long closed tail-race, a storage tank, a passage connecting said tank and race, in proximity to the water-wheel, and means for restrictingthe flow of water through said passage.

3. In combination with a water-power plant comprising a water-wheel and a long closed tail-race, a storage tank, a passage connecting said tank and race, in proximity to the water-wheel, means for restricting the flow of water through said passage, and means for modifying the water-pressure in said race in accordance with but at a more rapid rate than the change of ressure indicated by the change of waterevel in said tank.

4. In combination with a wa tenpower plant comprising a water-wheel and a long closed tail-race, a storage tank, a passage connecting said tank and race, in proximity to the water-wheel, means for restricting the flow of water through said passage, and a stand-pipe connected with said passage,

race in accordance with but at a more rapid serving to modify the water-pressure in said I rate than the change of pressure indicated by the change of Water-level in said tank.

5. In combination with a water-power plant comprising a water-wheel and a long closed tail-race, a storage tank having a 1 bottom opening, connected to said race, and I a stand-pipe within said tank and extending 1 into its bottom opening, leaving a restricted passage. 6. In combination with a water-power plant comprising a water-Wheel and a long I closed tail-race, a storage tank, a passage connecting said tank and race, in proximity to the water-wheel, means for restrictingi the flow of water through said passage, and l a stand-pipe connected with said passage,

- serving to modify the Water-pressure in said race in accordance with but at a more rapid rate than the change of pressure indicated by the change of water-level in said tank, said stand-pipe having an overflow outlet between its ends.

7. In combination with a watcw-power plant comprising a Watcr-wl'ieel and a long closed tail-race, a storage tank having a; bottom opening, a conduit connecting said l tank-opening and race, and a standpipc;

Within said tank and extending into its bottom opening, leaving a said stand-pipe 1 between its ends. I

8. In combination with a \vatenpowcr! plant comprising a Water-wheel and a long closed tail-race, a storage tank having a botf tom opening, a conduit connecting said, tank-opening and race, and a stand-pipe.

v restricted passage; having an overflow outlet said conduit by a restricted passage, and a stand-pipe also directly connected to said conduit.

10. in combination with a closed waterco-nduit, a differential hydraulic regulator consisting of a tank directly connected to said conduit by a restricted passage, and a stand-pipe also directly connected to said conduit. said siand-pipe having an opening between its ends in position to discharge Water into said tank ll. in combination with a closed water conduit, a diii erential l'iydranlic regulator consisting of a tan-l; linxing an opening con nectr-d to said conduit, and a stand-pipe ex tending into said awning in combination with a closed WBEQI conduit, :1 diti eiwintial hydraulic regulator ronsisting at a lanl; inn? an opening con-- nectcd to said cosi-eluit and a stanthpipe ending into said having a ndpipe comprising ctnfns with. an intermediate overflow passage,

In testimony c. has in presence of tow l atlix eignati: n i lit'r RA Mimi.) n Witnesses Eliot-1M; A. Prawns,

N. P. Lnonaan, 

